UN Secretary-General Ban Ki-moon has urged the Security Council to quickly approve an expanded cease-fire monitoring mission in Syria, while U.S. Secretary of State Hillary Clinton called for a new tougher UN resolution against Damascus.

Ban has been pushing for a 300-strong monitoring mission, while Syrian President Bashar al-Assad's regime says it will accept no more than 250 observers.

Speaking at the United Nations, Ban maintained that the situation in Syria remains extremely volatile, and that there has been "no progress" on the ground on the implementation of the week-old cease-fire, calling the situation "unacceptable."

"The situation [in Syria] remains highly precarious," he said. "Despite the government's agreement to stop all violence, we still see deeply troubling evidence that it continues."

"The past few days in particular has brought reports of renewed and escalating violence, including the shelling of civilian areas," he said.

However, Ban said Damascus officially accepted a preliminary protocol detailing the observer mission on April 19.

Paris Meeting

Ban urged the Syrian government again to offer "full cooperation, particularly in ensuring the full freedom of movement and unfettered access, safety and security of the personnel, as well as the use of key enabling assets such as helicopters and other transportation."

French Foreign Minister Alain Juppe said at the beginning of the meeting that UN observers must be deployed quickly to Syria, otherwise the UN Security Council will examine other options to end the crisis there.

Juppe said the failure of a UN-backed peace plan would put Syria on a path to a civil war that could spill out into the surrounding region.

Clinton meanwhile called for a new UN resolution authorizing an arms embargo and other sanctions if Syria fails to abide by the cease-fire.

Clinton said sanctions should also include travel and financial restrictions.

But she admitted that veto-holding Security Council member Russia would probably not allow such a motion to pass.

One alternative, she added, would be for NATO to invoke its mutual defense treaty in response to shelling by Syria on its northern border with alliance member Turkey.

The meeting in Paris also pledged to bring humanitarian assistance to Syria's refugees using "all envisageable mechanisms."

In Geneva, the head of the UN refugee agency, Antonio Guterres, said some 230,000 Syrians had fled their homes and taken refuge in other parts of the country since the March 2011 start of the uprising against Assad.